Bathtub plug



FIG. 1 is a top, front aid right side perspective view of a bathtub plug, showing my new design;

FIG. 2 is bottom, rear and left side perspective view;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof; and,

FIG. 6 is a cross-sectional view taken from line 6-6 of FIG. 4.

The broken lines in the drawings illustrate the portions of the bathtub plug, which form no part of the claimed design. 

CLAIM The ornamental design for a bathtub plug, substantially as shown and described. 